Isocyanate modified polymers



Patented Jan. 13, 1953 ISOCYANATE MODIFIED POLYMERS Nelson V. Seeger,Cuyahoga Falls, Ohio, assignor to Wingfoot Corporation, Akron, Ohio, acorporation of Delaware No Drawing. Application September 29, 1950,Serial No. 187,696

18 Claims. 1

This invention relates to synthetic polymeric materials and to methodsof preparing the same. More particularly it relates to modifiedpolyesters which possess elastomeric, rubber-like qualities and toimproved methods for their preparation. Still more particularly itrelates to polyesters which have been modified by reaction with anorganic diisocyanate and an additional bifunctional reactant to form aninterpolymer.

The polyesters are formed, for example, by the condensation of a dibasiccarboxylic acid with a glycol. The condensation reaction proceeds withthe elimination of water to yield a linear polyester which is usually ofa viscous, syrupy or waxlike consistency at room temperature.

As is determined by the materials and amounts thereof used in itsformation, the linear polyester may contain terminal carboxyl o1-hydroxyl groups depending upon whether an acid or a glycol was the lastcompound to react in the formation of the linear molecule. The linearpolyester is then lengthened further by reaction between thesehydrogen-bearing terminal groups and a bifunctional material reactivetherewith, such as a diisocyanate, with the formation of what may bereferred to as a chain-extended polymer. The linkages formed by thereaction of the terminal groups of the polyester with a diisocyanate,for example, are a urethane linkage (-O!lN--) in the case of a terminal--OH group, and principally an amide linkage CJI in the case of aterminal COOH group. Since each of these linkages contains availablehydrogen for reaction with an additional bifunctional material such as adiisocyanate, it is possible to cross-link the chain-extended polymer atvarious points along its chain.

Depending upon many variables in their preparation, the modifiedpolymers will vary considerably in their physical characteristics toinclude soft wax-like materials, elastomeric rubher-like materials, hardfiber-forming materials, tough leather-like materials and hard,infusible resinous materials. The present invention pertains to animproved modified interpolymer which has elastomeric, rubber-likeproperties.

The cross-linking or curing which occurs as the result of reactionbetween the NCO groups of the diisocyanate and the available reactivehydrogen in the chain-extended polymer is accompanied by the generationof gas. This gas, which is believed to be CO2, remains trapped in themass with resulting blisters or bubbles in the cured product. Toeliminate the trapped gas, it has been necessary to pre-cure thematerial, during which time most of the gas is generated, remove thematerial from the oven or press, remill the material to dissipate thetrapped gas, and return the gas-free material to the press, or oven, forfinal cure. This procedure is both time-consuming and expensive becauseof the many handling operations required to produce a satisfactory curedproduct. It is therefore an object of this invention to reduce the timeof cure required to produce a satisfactory product from modifiedpolyesters. It is a further object to eliminate the blisters or gasbubbles in the cured product without the necessity of pre-cure andrehandling of the raw material. It is another object to reduce thenumber of handling operations in the fabrication of a satisfactory curedproduct. Still another object is to produce a new modified polyesterwhich is fast curing at elevated temperatures but which does not hardenor cure appreciably faster than the usual modified polyesters at normalroom temperatures. Other objects will appear as the descriptionproceeds.

The particular polyesters used in the practice of this invention aresimilar to those described in my co-pending application, Serial No.170,055. As described therein, the unmodified polyester is prepared inits simplest form from two bifunctional ingredients, one being a dibasiccarboxylic acid and the othcrbeing a glycol. In addition, a

wide variety of complex polyesters may be formed by the reaction of aplurality of acids and glycols. In preparing the polyester it ispossible to use ester mixtures such as a physical mixture of ethyleneadipate and 1,2-propylene adipate as well as mixed esters such as thatresulting from the reaction of a mixture of ethylene glycol and 1,2propylene glycol with adipic acid. The reaction proceeds with theelimination of water to yield a long chain molecule containing asuccession of ester groups and terminated by either hydroxyl or'carboxyl radicals. The reaction may be represented by the followingequation:

II II ao-a on) n(HO-URUOH) H H n o-R-0-c-R'c ..oH at-01120 wherein R andR denote divalent organic radicals such as hydrocarbon radicals, and nis a positive whole number denoting the degree of polymerization of thepolyester formed.

In the preparation of the polyester, it is possible to obtain productsof varying molecular Weight, depending in part upon the molecular weightof the reactants and in part upon the degree of polymerization of thereactants or the number of ester units in the polyester chain. While theaverage molecular weight of the polyester will,

of course, vary depending upon the particular 1 acids and glycols used,the average number of these ester groups present in the polyester chainmust be held within certain limits in ordcrto permit subsequentmodification to yield a satisfactory rubber-like polymer. A convenientmethod of measuring the degree of polymerization of the polyester is todetermine th average number of carboxyl and hydroxyl groups in a givenamount of the linear extended polyester.

The acid number (millograms of KOH per gram of. polyester usingphcnolphthalein as an indicator) is av measure of the number of terminalcarboxyl groups in the polyester. The hydroxyl number, which is ameasure of the number of terminal hydroxyl groups present, is determinedI by adding pyridine and acetic anhydride to the polyester and titratingthe acetic acid formed with KOH as described in Ind. Eng. Chem. Anal,Ed. 16, 541-49 and in Ind. Eng. Chem. Anal. Ed. 1'7, 394 (.1945). asmilligrams of KOH per gram of polyester. The sumof the acid number andthe hydroxyl number, which will be referred to as. the reactive number,is an. indication of the average number of terminal groups present inthe polyester product which in turn is an indication of the number ofmolecules in the mass and the degree of polymerization. A polyestercontaining long chain. molecules will have a relatively low reactivenumber, while a polyester containing short chain molecules will possessa higher reactive number.

As described in. my oo-pending application,

The hydroxyl number is defined modified chain-extended polyester issubsequently cross-linked and cured by reaction with additionaldiisocyanate, the problem of gas forma tion or blisters arises. It hasnow been discovered that the addition of a small amount of anotherbifunctional additive, in addition to the diisocyanate added tochain-extend the unmodified polyester, will produce an uncuredchainextended modified polyester which will cross-link or cure, whenreacted with additional diisocyamate, in a shorter time and with theelimination of blisters in the cured product.

The bifunctiona-l additives which have been found to produce thisunexpected result may be represented by the general formula XR.X' inwhich R" represents a divalent organic radical such as an aliphatic, oraromatic, divalent radical, X represents either a NI-I2 or a COOH groupand X is a functional group containing at least one active, availablehydrogen such as a primary amino, secondary amino, carboxyl, or hydroxylgroup. Compounds falling within this definition would include diamines,dibasic. carb-oxylic acids, amino acids, hydroxy acids, amino alcohols,and certain ureas, guanidines, and thioureas which contain -NH2 groups.According to the practice of this invention, the bifunctional additivedescribed must be used in an amount such that the sum of NH2 equivalentsand -COO. .I- equivalents present in the bifunctional additive shall befrom 0.06 to 0.48 equivalents per mol of polyester. Smaller amountsresult in a finished product whose cure rate and blister forming havenot been materially reduced. Greater amounts produce an uncured modifiedproduct which does not possess the required binaging or processingproperties as described in my co-pending application referred to above.

Using the polyester formed as represented by Equation 1 above, thereactions between the polyester, the diisocyanate and the bifunctionalad.- ditive may typically be represented by the following equations:

1 l H a 20 mol per cent excess of glycol in the preparation of thepolyester.

In the chain extension of a polyester possessing an acid number andhydroxyl number within the critical range indicated, a controlled amountof a particular diisocyanate is added to the polyester as described inmy co-pending application,

Serial No. 170,055. When this diisocyanatein which R," and R' representdivalent organic radicals such as aliphatic or aromatic radicals and mrepresents a positive whole number denoting the number of segments inthe modified chain-extended inter-polymer.

The underlined hydrogens represent those available for reaction with the-NCO groups in the polyisocyanates used to cross-link or cure thechain-extended polyester. The products resulting from the reactionsrepresented by the above equations may be referred to as (2)polyesteramide urea urethanes, (3) polyester amideurethane-urethanes,and (4) polyester-amideamide-urethanes. Other configurations are alsopossible if dibasic carboxylic acids or hydroxy acids are used as theadditional bifunctional reactant. In each case an interpolymer is formedside of the polyester segments in the chain-extended polyester. Thearrangement of the amide, urea, and urethane linkages along the chaincan be either random or ordered depending upon the manner in which thebifunctional additive is reacted with the polyester-diisocyanatemixture. If all of the additive and diisocyanate areadded together tothe polyester, a random interpolymer results. If the additive is reactedwith the polyester-diisccyanate mixture in increments, an or deredinterpolymer results. In either case a product is formed which will curefaster than'the polyester modified by diisocyanate only and which willnot require additional handling to remove trapped gas. I

The particular diisocyanates with which this invention is concerned are4,4'-diphenyl di'isocyanate, 4,4'-diphenylene methane diisocyanate,dianisidine diisocyanate, 4,4'-tolidine diisocyanate, 1,5-naphthalendiisocyanate, 4,4-diphenyl ether diisocyanate, and p-phenylenediisocyanate. It has been pointed out in my co-pending applicationreferred to above that the critical range of diisocyanates which must beused to modify the polyester in order to produce a satisfactoryrubber-like polymer is from 0.70 to 0.99 mols of diisocyanate per mol ofpolyester. An additional amount of diisocyanate is required here tosatisfy the active hydrogens present in the bifunctional additive.Therefore, the total amount of diisocyanate required to chain-extend thepolyester in order to produce a processible,

storable, fast-curing interpolymer which does notproduce blisters in thecured product will be equal to the sum of from 0.70 to 0.99 mols per molof polyester and a molar amount equivalent to the mols of bifunctionaladditive used.

Of the particular diisocyanates shown, the 'preferred ones arel,4'-diphenyl diisocyanate, 1.5- naphthalene diisocyanate, anddiphenylene methane diisocyanate, the use of any of which produces aninterpolymer which, when cured, possesses outstanding physicalproperties. Itis possible to employ a mixture of diisocyanates in thepreparat on of the chain-extended polyester so long as the total amountof the diisocyanate used,

falls within the range indicated. While certain diisocyanates will notproduce the desired results if used in an amount covered by the criticalrange specified, it is to be understood that those listed are notnecessarily the only diisocyanates which are operative for the purposesof this invention, but rather represent those which have actually. beentested and found to produce the desired re-I sults when employed in anamount covered byv the critical range indicated.

After the interpolymer has been formed,,it is prepared for curing byadding more diisoc'yanate effect a cure must be controlled so as toprovide a total-number of NC() equivalents present in thecured material,including that added in the formation of the chain-extended polyester,equal to the sumof from'2.80 to 3.20 equivalentsof NCO per mol ofpolyester and twice the molar amount ofbifunctional additive used in thepreparation of the interpolymer. Smaller amounts ofpolyisocyanate addedto cure th mterpolymer will result in an uncured product. The use ofgreater amounts is a waste of material with no improved properties inthe cured product, and in some cases produces a cured material havingproperties more resinous than rubher-like. If a triisocyanate ortetraisocyanat is used toefiect a cure, not as much material, on

a mol basis, need be used since the curing or cross-linking of thelinear molecules depends upon the number of NCO groups present in thecuring agent. For example, if 0.50 mols of a diisocyanate gives asatisfactory cure of the interpolymer, the use of approximately 0.25mole of a tetraisocyanate will result in a similar state of cure.

the preparation of the polyester.

The actual curing of the interpolym'er is accomplished by methodsfamiliar to those skilled in the art. The time and temperature requiredto effect the best cure for any particular material will, of course,vary as in the case with the during of conventional natural rubbercompounds. The cure for best results should be accomplished by the useof dry heat since exposure of themterpolymer to hot water or steamresults in a partial degradation of the cured material.

A variety of acids and glycols may be used in Any dibasic carboxylicacid containing at least 3 carbon atoms, and preferably those whosecarboxyl groups are attached to terminal carbons, may be used includingsuccinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, malonic,brassylic, citric, tartaric, maleic, malic. 'fumaric, dilinoleic,thiobutyric, diphenic, isophthalic, 'terephthalic,hexahydroterephthalic, p-phenylene diacetic, dihydromuconic, and B-methyladipic acids. For best results the un-' saturated acids should beused, in mixture with a saturated acid, in "an amount not to exceed 5mol per cent. The presence of a small amount of unsaturation in thepolyester is often desirable if cheaper curing orcross-linking agents,such as for example, sulfur, "benzoyl peroxide *or tertiary butyl'hydroperoxide, are to be used; Higher degrees of unsaturation in thepolyester result in cured products which do not have the outstandingphysical properties possessed by the products produced from polyesterscontaining no unsaturation or'a relatively small amount of unsaturation.

Any glycol may be used in the formation of the polyester includingethylene, propylene 1,2,

'- propylene 1,3, diethylene, triethylene, butylene.

pentamethylene, hexamethylene, decamethylene, dodecamethylene, and N,l.T-diethanolaniline, glycerine mono ethers, and thiodiglycol.

Specific examples of the bifunctiona-l additives wh ch may be used inthe practice of this invention are: (1) The diamines which contain atleast one primary amino group includin as re resentative examples.ethylene, propylene 1,2, tetramethylene 1,4, hexamethylene 1,6,decamethylene 1,10, isopropyl amino propylamine, 3,3-diamino dipropylether, benzidine, diamino-diphenyl methane, p-phenylene, m-phenylene,and 2,4. tolylene diamine. V w '(2) 'I'he'primary amino alcoholsincluding, as

representative examples, ethanolamine, 3"amino.-. propanol. 4amino-butanol, 6 amino-hexanol, and 10 amino-decanol.

(3) The dibasic carboxylic acids including, as representative examples,those listed under the materials available for the preparation of thepolyester.

(4) The ureas, guanidines, and thioureas containing an -NH2 groupincluding, as representative examples, urea, thiourea, phenyl urea,phenyl guanidine, phenyl thiourea, methyl urea, and methyl thiourea.

(5) The amino carboxylic acids including, as representative examples,glycine, amino proprionic, aminocaproic, aminononanoic, andaminoundecanoic acids.

(6) The hydroxy carboxylic acids including, as representative examples,glycollic, hydroxycaproic, and hydroxydecanoic: acids.

Any mixture of these bifunctional additives may be used so long as thetotal number of -COOH and NH2 equivalents is held Within the criticalrange indicated.

Listed below are the reactants which are used to form particularpolyesters which, when modified by diisocyanate and one or morebifunctional additives and subsequently mixed with a suitable curing orcross-linking agent, will produce a material which is fast to cure atelevated temperatures, slow to cure at room temperature, and free ofblisters.

1. Ethylene glycol plus adipic acid.

2. Propylene glycol 1,2 plus adipic acid.

3. Ethylene glycol (80 mol per cent), propylene glycol 1,2 (20 mol percent) plus adipic acid.

4. Ethylene glycol (80 mol per cent), propylene glycol 1,2 (20 mol percent) plus azelaic acid.

5. Ethylene'glycol (80 mol per cent), propylene glycol 1,2 (20 mol percent) plus sebacic acid.

6. Ethylene glycol (80 mol per cent), propylene glycol 1,2 (20 mol percent) plus dilinoleic acid (20 mol per cent), adipic acid (80 mol percent).

7. Ethylene glycol (80 mol percent), glycerine monoethyl ether (20 molper cent), plus adipic acid.

8. Ethylene glycol (80 mol per cent), butylene glycol 1,4 (20 mol percent), plus adipic acid.

9. Ethylene glycol (80 mol per cent), propylene glycol 1,3 (20 mol percent) plus adipic acid.

10. Ethylene glycol (80 mol per cent), pentane diol 1,5 (20 mol percent) plus adipic acid.

11. Ethylene glycol (80 mol per cent), glycerine monoisopropyl ether (20mol per cent) plus adipic acid.

12. Ethylene glycol (80 mol percent), propyle ene glycol 1,2 (20 mol percent) plus maleic acid- (from 3 to 6 mol per cent), adipic acid (from 97to 94 mol per cent).

13. Ethylene glycol (80 mol per cent), propylene glycol 1,2 (from 18 to5 mol per cent), dihydroxyethyl aniline (from 2 to 15 mol per cent) plusadipic acid.

14. Ethylene glycol (80 mol per cent), diethylene glycol (20 mol percent) plus adipic acid.

15. Ethylene glycol (from 90 to 10 mol per cent), propylene glycol 1,2(from 10 to 90 mol per cent) plus adipic acid.

16. Ethylene glycol (from 90 to 10 mol per cent), propylene glycol 1,2(from 10 to 90 mol per cent) plus azelaic acid.

Of particular interest are the interpolymers resulting from (1)Polyethylene adipate modified by 4,4- diphenyl diisocvanate,1,5-naphthalene diisocyanate, 4,4'-diphenylene methane diisocyanate, or

mixtures thereof, and by ethylene diamine, tetramethylene diamine,hexamethylene diamine, ethanol amine, benzidine, 4,4'-diamino diphenylmethane or mixtures thereof.

(2) Polypropylene 1,2 adipate modified by 4,4- diphenyl diisocyanate,1,5-naphthalene diisocyanate, 4,4'-diphenylene methane diisocyanate, ormixtures thereof, and by ethylene diamine, tetramethylene diamine,hexamethylene diamine, ethanol amine, benzidine, 4,4-diamino diphenylmethane or mixtures thereof.

(3) Polyethylene (80 mol per cent) propylene 1,2 (20 mol per cent)adipate modified by 4,4- diphenyl diisocyanate, 1,5-naphthalenediisocyanate, 4,4='-diphenylene methane diisocyanate, or mixturesthereof, and by ethylene diamine, tetramethylene diamine, hexamethylenediamine, ethanol amine, bendizine, 4,i'-diamino diphenyl methane ormixtures thereof.

,(4) Polyethylene (80 mol per cent) propylene 1,2 (20 mol per cent)azelate modified by 4,4-

. diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylenemethane diisocyanate, or mixtures thereof, and by ethylene diamine,tetramethylene diamine, hexamethylene diamine, ethanol amine, bendizine,4,4-diamino diphenyl methane or mixtures thereof.

These interpolymers, when cured, have been found to possess outstandingphysical properties.

The elastomeric reaction products prepared according to the practices ofthis invention are, in general, useful in those applications wherenatural rubber or rubber-like materials are used. In particular they maybe used in tires, belts, hose, sheet packing, gaskets, molded goods,floor mats, dipped goods, sheeting, tank lining, soles, heels, coveredrolls, and other mechanical and industrial goods.

The following examples in which parts are by weight are illustrative ofthe preparation of the modified polyesters according to the teachings ofthis invention.

EXAMPLE 1 Preparation of typical polyester Adipic acid (3515 parts) wasplaced in a 5 liter, B-necked flask fitted with a stirrer, thermo-couplewell, gas inlet tube, distilling head, and condenser. To the acid wereadded 1064 parts of ethylene glycol and 869 parts of propylene 1,2glycol. The molar ratio of dibasic acid to glycol is 1:l.19. The mixturewas heated to 130?-160 C.

until most of the water had distilled off. he emp ra re w s h r du lly rised to 200 0., the pressure being gradually reduced to 20 mm. andnitrogen being bubbled through the melt. After 23 /2 hours a soft whitewaxy solid was obtained. Determinations showed the, acid rgllfigbgr tobe 3.5 and the hydroxy number to EXAMPLE 2 Preparation of modifiedinterpolymer 9 EXAMPLE 3 EXAMPLE 4 This interpolymer was prepared in thesame manner as Example 2 except ethanolamine was used as a molarreplacement for hexamethylene diamine. The processing characteristics ofthe material were good.

EXAMPLE 5 Thi interpolymer was prepared in the same manner as Example 2except 0.24 mol of ethanolamine per mol of polyester and 1.19 mols of4,4- diphenyl diisocyanate per mol of polyester were used. The reactedmaterial possessed excellent processing characteristics on a rubbermill.

The uncured interpolymer prepared according to Examples 2, 3, 4, and 5were mixed with 0.55 mol of additional 4,4-dipheny1 diisocyanate andcured for minutes and 300 F. with no precure. The cured materialcontained no blisters. The results obtained from tests showed the curedmaterial to have excellent physical properties. Similar polymersprepared without the b'ifunctional additive resulted in cured materialwhich was badly blistered unless the polymer was precured for 30 minutesat 300 F., removed from the press, remilled to remove the blistersformed, and returned to the press for final cure.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent tov thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

I claim: 7 a

1. The elastomeric reaction product resulting from the reaction of amixture comprising: A, a polyester prepared from bifunctionalingredients including at least one dibasic carboxylic acid containing atleast 3 carbons and at least one glycol, said polyester having ahydroxyl number from 40 to 100 and an acid number from 0 to '7, and B,at least one bifunctional additive selected from the group consisting ofdiamines, amino alcohols, dibasic carboxylic acids, amino carboxylicacids, hydroxy carboxylic acids, and the ureas, guanidines, andthioureas containing a primary amino group, said bifunctional additivecontaining at least one reactive group selected from the groupconsisting of primary amino and carboxyl, said bifunctional additivebeing used in an amount such that the total number of NH2 and -COOHequivalents present in said bifunctional reactant shall be from 0.06 to0.48 equivalent per mol of polyester, and C, at least one diisocyanateselected from the group consisting of 4,4 diphenyl diisocyanate, 4,4diphenylene methane diisocyanate, dianisidine diisocyanate,4,4-'tolidine diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylether diisocyanate, and pphenylene diisocyanate, the diisocyanate beingused in an amount equal to the sum of from 0.70 mol to 0.99 mol ofdiisocyanate per mol of polyester and the molar amount of diisocyanateequivalent to the mols of said bifunctional additive used.

2. The elastomeric reaction product resulting from the reaction of amixture comprising:

A, a polyester prepared from biiunctional ingredients including adipicacid, ethylene glycol and propylene glycol, said polyester having ahydroxyl number from 40 to 100 and an acid number from 0 to 7, and B, atleast one diamine containing at least one primary amino group, saiddiamine being used in an amount such that the total number of primaryamino equivalents present in said diamine shall be from 0.06 to 0.48equivalent per mol of polyester, and C, at least one diisocyanateselected from the group consisting of 4,4-diphenyl diisocyanate,4,4'-diphenylene methane diisocyanate, dianisidine diisocyanate,4,4'-tolidine diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylether diisocyanate, and p-phenylene diisocyanate, the diisocyanate beingused in an amount equal to the sum of from 0.70 mol to 0.99 mol ofdiisocyanate per mol of polyester and a molar amount of diisocyanateequivalent to the mols of said diamine used.

3. The elastomeric reaction product resulting from the reaction productof a mixture comprising: A, a polyester prepared from approximately molpercent of ethylene glycol, approximately 20 mol percent of propyleneglycol 1,2, and adipic acid, said polyester having a hydroxyl numberfrom 50 to 60 and an acid number from 0 to 7, and B, benzidine, saidbenzidine being used in an amount ranging from 0.03 to 0.24 mol per molof polyester and C, 4,4-diphenyl diisocyanate, said diisocyanate beingused in an amount equal to the sum of from 0.90 to 0.99 mol per mol ofpolyester and a molar amount equivalent to the mols of benzidine used.

4. The process for making an elastomeric reaction product whichcomprises reacting together a mixture of: A, apolyester prepared frombifunctional ingredients including at least one dibasic carboxylic acidcontaining at least 3 carbons and at least one glycol, said polyesterhaving a hydroxyl number from 40 to and an acid number from 0 to 7, andB, at least one bifunctional additive selected from the group consistingof diamines, amino alcohols, dibasic carboxylic acids, amino carboxylicacids, hydroxy carboxylic acids, and the ureas, guanidines, andthioureas containing a primary amino group, said bifunction'al additivecontaining at least one reactive group selected from the groupconsisting of primary amino and carboxyl, said bifunctional additivebeing used in an amount such that the total number of NH2 and COOHequivalents present in said bifunctional reactant shall be from 0.06 to0.48 equivalent per mol of polyester, and C, at least one diisocyanateselected from the group consisting of 4,4-diphenyl diisocyanate,4,4'-diphenylene methane diisocyanate, dianisidine diisocyanate,4,4'-tolidine diisocyanate, 1,5- naphthalene diisocyanate, 4,4-diphenylether diisocyanate, and p-phenylene diisocyanate, the diisocyanate beingused in an amount equal to the sum of from 0.70 mol to 0.99 mol ofdiisocyanate per mol of polyester and the molar amount of diisocyanateequivalent to the mols of said bifunctional additive used.

5. The process for making an elastomeric reaction product whichcomprises reacting together a mixture of: A, a polyester prepared frombifunctional ingredients including adipic acid, ethylene glycol andpropylene glycol, said polyester having a hydroxyl number from 40 to 100and an acid number from 0 to 7, and B, at least one diamine containingat least one primary amino group, said diamine being used in an amountsuch that the total number of primary amino equivalents present in saiddiamaine shall be from 0.06 to 0.48 equivalent per mol of poly ester,and C, at least one diisocyanate selected from the group consisting of4,4'-diphenyl diisocyanate, 4,4-diphenylene methane diisocyanate,dianisidine diisocyanate, 4,4'-tolidine diisocyanate, 1,5-naphtha1enediisocyanate, 4,4- diphenyl ether diisocyanate, and p-phenylenediisocyanate, the diisocyanate being used in an 4 amount equal to thesum of from 0.70 mol to 0.99 mol of diisocyanate per mol of polyesterand a molar amount of diisocyanate equivalent to the mols of saiddiamine used.

6. The process for making an elastomeric reaction product whichcomprises reacting together a mixture of A, a polyester prepared fromapproximately 80 mol percent of ethylene glycol, approximately 20 molpercent of propylene glycol 1,2, and adipic acid, said polyester havinga hydroxyl number from 50 to 60 and an acid number from 0 to 7, and B,bendizine, said benzidine being used in an amount ranging from 0.03 to0.24 mol per mol of polyester and C, 4,4'-diphenyl diisocyanate, saiddiisocyanate being used in an amount equal to the sum of from 0.90 to0.99 mol per mol of polyester and a molar amount equivalent to the molsof benzidine used.

7. The process for making a cured elastomeric composition whichcomprises reacting the product prepared according to claim 5 with asufficient amount of at least one polyisocyanate to bring the totalnumber of NCO equivalents present in said cured mixture to the sum offrom 2.80

to 3.20 equivalents of -NCO per mol of said polyester and twice themolar amount of bifunctional additive used in the preparation of saidelastomeric reaction product.

8. The cured elastomeric composition prepared according to the processdefined by claim 7.

9. An article comprising the cured elastomeric composition defined byclaim 8.

10. The cured elastomeric composition defined by claim 8 in which thepolyester is prepared from adipic acid.

11. The cured elastomeric composition defined by claim 8 in which thepolyester is prepared from azelaic acid.

12. The elastomeric reaction product defined by claim 1 in which thebifunctional additive used is diamino diphenyl methane.

13. The elastomeric reaction product defined by claim 12 in which thepolyester is prepared from adipic acid.

14. The elastomeric reaction product defined by claim 1 in which thebifunctional additive used is tolylene 'diamine.

15. The elastomeric reaction product defined by claim 14 in which thepolyester is prepared from adipic acid.

16. The elastomeric reaction product defined by claim 1 in which thediisocyanate used is 1,5- naphthalene diisocyanate.

17. The elastomeric reaction product defined by claim 16 in which thepolyester is prepared from adipic acid.

18. The elastomeric reaction product defined by claim 1 in which thepolyester is prepared from azelaic acid.

NELSON V. SEEGER.

'REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,333,639 Christ et a1. Nov. 9,1943 2,437,046 Rothrock et a1. Mar. 2, 1948 OTHER REFERENCES Ser. No.397,741, Schlack (A. P. (3.), published Apr. 20, 1943.

Bayer et a1., Rubber Chem. and Techn. Oct.- Dec. 1950, pp. 812-835(translated from Angewandte Chemie, vol. 62 No. 3, pp. 57-66, Feb. 7.1950).

1. THE ELASTOMERIC REACTION PRODUCT RESULTING FROM THE REACTION OF AMIXTURE COMPRISING: A, A POLYESTER PREPARED FROM BIFUNCTIONALINGREDIENTS INCLUDING AT LEAST ONE DIBASIC CARBOXYLIC ACID CONTAINING ATLEAST 3 CARBONS AND AT LEAST ONE GLYCOL, SAID POLYESTER HAVING AHYDROXYL NUMBER FROM 40 TO 100 AND AN ACID NUMBER FROM 0 TO 7, AND B, ATLEAST ONE BIFUNCTIONAL ADDITIVE SELECTED FROM THE GROUP CONSISTING OFDIAMINES, AMINO ALCOHOLS, DIBASIC CARBOXYLIC ACIDS, AMINO CARBOXYLICACIDS, HYDROXY CARBOXYLIC ACIDS, AND THE UREAS, GUANIDINES, ANDTHIOUREAS CONTAINING A PRIMARY AMINO GROUP, SAID BIFUNCTIONAL ADDITIVECONTAINING AT LEAST ONE REACTIVE GROUP SELECTED FROM THE GROUPCONSISTING OF PRIMARY AMINO AND CARBOXYL, SAID BIFUNCTIONAL ADDITIVEBEING USED IN AN AMOUNT SUCH THAT THE TOTAL NUMBER OF-NH2 AND -COOHEQUIVALENTS PRESENT IN SAID BIFUNCTIONAL REACTANT SHALL BE FROM 0.06 TO0.48 EQUIVALENT PER MOL OF POLYESTER, AND C, AT LEAST ONE DIISOCYANATESELECTED FROM THE GROUP CONSISTING OF 4,4''- DIPHENYL DIISOCYANATE,4,4''-DIPHENYLENE METHANE DIISOCYANATE, DIANISIDINE DIISOCYANATE,4,4''-TOLIDINE DIISOCYANATE, 1,5-NAPHTHALENE DIISOCYANATE,4,4''-DIPHENYL ETHER DIISOCYANATE, AND PPHENYLENE DIISOCYANATE, THEDIISOCYNATE BEING USED IN AN AMOUNT EQUAL TO THE SUM OF FROM 0.70 MOL TO0.99 MOL OF DIISOCYANATE PER MOL OF POLYESTER AND THE MOLAR AMOUNT OFDISSOCYANATE EQUIVALENT OF THE MOLS SAID BIFUNCTIONAL ADDITIVE USED.